Fluid pressure motor



Dec. 2G, 1955 E. F. NxcHoLs ZZAQ FLUID PRESSURE MOTOR Filed July 13 195] United States Patent O FLUID PRESSURE MOTOR Elton F. Nichols, Michigan City, Ind., assignor to Charles A. Sprague, Michigan City, Ind.

Application July 13, 1951, Serial No. 236,651

8 Claims. (Cl. 121-150) This invention relates to improvements in uid pressure motors, and more particularly to uid pressure l'motors of the reciprocating type which are adapted for use upon automobiles to drive windshield wipers.

Reciprocating fluid pressure motors customarily include at least three primary operating parts, that is, a pressure responsive reciprocating or oscillating part, valve mechanism for controlling the ow of fluid to and from the pressure responsive parts, and a mechanical connection between the pressure responsive part and the valve means which serves to actuate the valve by changing its position or setting as the pressure responsive part nears the end of each stroke. The mechanical connection or valve actuator must be a lost motion device so that it does not affect the setting of the parts during the major portion of each stroke. Other requirements for such a valve actuator are that it must have a quick throw, must -be reversible, and must have only two operative positions.

A mechanical connection device or valve actuator is sub- 'ject to wear and failure, and its fabrication and assembly with other parts of a uid pressure motor during manu- Vfacture constitute a substantial proportion of the total items or factors which determine the cost of manufacture of the device.

The primary object of this invention is to simplify the construction and reduce the cost of manufacture of the fluid pressure motor by so arranging a fluid pressure responsive member and valve means with respect to the uid passages in the motor housing which constitute a uid circulating system as to obviate the necessity for a mechanical valve actuator.

A further object is to provide a device of the character having casing means with a valve chamber and a second or working chamber in which, respectively, a control valve and a pressure responsive member shift bodily, and in which each of said members responds to fluid pressure as exerted thereagainst and directed through passages controlled by the other.

A further object is to provide a device of this character which is simple in construction, comparatively inexpensive, and in which the number of working or moving parts is reduced, compared to previous constructions.

Other objects will be apparent from the following specification.

In the drawing:

Fig. l is a longitudinal sectional view taken on line 1 1 of Fig. 3.

Fig. 2 is a transverse sectional view taken on line 2 2 of Fig. 1.

Fig. 3 is a transverse sectional view taken on line 3 3 of Fig. 1.

Fig. 4 is a longitudinal sectional view taken on line 4 4 of Fig. 1.

Fig. 5 is a fragmentary view similar to Fig. 1 and illustrating a modified embodiment of the invention.

Referring to the drawing which lillustrates vpreferred embodiments of the invention, the numeral designates a housing. As here illustrated, the housing is unitary 2,727,494 Patented Dec. 20, 1955 and is of generally elongated, substantially cylindrical form, being provided with a cylindrical body portion 12 having a longitudinal thickened wall portion 14. In the thickened portion 14 is formed a cylindrical chamber 16, preferably extending full length. The housing 10 may be of any suitable form, and may be formed in two parts each including one of the chambers 13 and 16. The housing will preferably be provided with end flanges 18 into which may be anchored securing means, such as screws 20, which serve to secure end plates 22 in place. Gasket members 24 are preferably interposed between the end plates 22 and the adjacent ends of the housing 10 so as to seal the main cavity 13 of the cylindrical body 12 and the secondary cavity or chamber 16.

The body 10 will preferably be provided with a pair of axially aligned collars or sleeves 26 and 28 adapted to journal a shaft 3G. The shaft 3i) is preferably provided at one end with an anchor surface 32 which is preferably 'serrated and which may be tapered as illustrated, and

which is adapted to be gripped by a windshield wiper blade-mounting arm (not shown). The anchor surface 32 may be positioned inwardly from a threaded end portion 34 adapted to mount a lock nut for holding the windshield wiper arm upon the part 32. The opposite end of the shaft 30 may mount a hand lever 36 held in place by a nut 38. It will be understood, however, that the use of the lever 36 is optional. The collars 26, 28 are so positioned that the shaft 3i) will be offset from the longitudinal axis of the chamber 13 and will extend transversely thereacross.

An access opening 49 may be provided in the body part 12 adjacent to and between the sleeves 26 and 28 and preferably at the longitudinal center of the body. The access opening 40 is preferably outlined by an outwardly projecting flange 42 and is spanned by a closure plate 44 secured to the shoulder 42 by securing means 46, such as screws.

A pressure responsive member in the nature of a double-ended piston unit is shiftable in the working chamber 13 of the housing. This unit may take any form found suitable, and, as here illustrated, comprises a pair of opposed end members 50, each having a circumferential groove 52 formed therein to receive an annular resilient sealing member 54 of well known type, one forni of which is commonly known as an O-ring. The end members 50 may have clearance in the chamber 13, and the sealing action at each is provided solely by the sealing members 54 which are retained in their grooves and prevent the leakage therepast of fluid, such as air or gas.

A central longitudinal part 56 interconnects the two end parts 50, the same being preferably of channel shape in cross-section, as illustrated in Fig. 2. The median portion of the longitudinal connector 56 is provided with teeth 58 and defines a rack. Flanges 60 are located at opposite sides of the rack for purposes to be described. A gear 62, preferably mutilated or of partial character only, is flxedly anchored to the shaft 30 by a set screw or other locking member 64. Consequently, as the piston unit shifts or reciprocates in the chamber 13, the meshing of the gear 62 with the rack 58 will cause the shaft 30 to be rocked or rotated for a part only of one revolution, thus actuating the member to be driven thereby, such as a windshield wiper blade or arm.

A valve unit 70 of the spool type is shiftable and the valve chamber 16, for example, is reciprocable endwise. The spool 70 is of a length lslightly less than the overall length of the chamber 16 and has a plurality of enlargements or shoulders 73 formed thereon in longitndinaly spaced relation and each provided with a circumferential groove. These circumferential grooves mount and retain annular resilient sealing members 74, 76, 73 and 80, respectively. In the form shown, the seals 76 and 73 are ing the end of that stroke for any given setting of the valve before it uncovers the port which permits the pressure-responsive change cf setting of the valve unit to cause reversal of the direction of ow of uid under pressure in the operating circuit and resultant reversal of the direction of operation of the main or working piston unit of the device. it will be apparent, however, that the stroke of the Working piston will be controlled by the spacing between the ports 93 and 99. The location of the ports 98 and 99 also determines the portion of the working chamber in which the piston unit will reciprocate. It is apparent, therefore, that if the ports 98 and 99 are not arranged symmetrically, that is, if opposite ports are located at different distances from the opposite ends of the Working chamber, the piston unit will move through a path such that it approaches at one end of its stroke closer to one end wall 20 than its approach toward the opposite end wall in its opposite stroke. These characteristics will permit each unit to be constructed to serve the purposes best suited for the particular installation. At the same time it will be possible to vary the stroke of the wiper blade upon the windshield wiper, if that is desired, by releasing the set screw or other securing member 64 and changing the orientation of the shaft 3() with respect to the pinion 62 and then retightening said set screw or locking member 64.

While the device is best suited for use with compressed air, it will be apparent that it will operate also, but in a reverse fashion, when the socket 82 is connected to a source of suction, that is, to a line at sub-atmospheric pressure. ln this connection, however, a slight change in the location of the passages 86, 8S and 89 is necessary, as illustrated in Fig. 5, wherein the left-hand longitudinal passage 86 is illustrated as extending to a port 88 located slightly to the right of the longitudinal center of the valve chamber 16, that is, to the right of the port or aperture 84. Similarly, the right-hand longitudinal passage 87 is illustrated as extending to a port 89 located at the left of the longitudinal center of the valve chamber 16 and to the left of the aperture 84.

The operation of the modied embodiment of the invention illustrated in Fig. 5, when the socket 82 is connected with a source of iluid under sub-atmospheric pressure, is as follows: Assuming that the valve is in the position illustrated in Fig. 5, air under pressure enters at the port 94 and passes through the portion of the valve chamber 16 between the seals 74 and 76 to enter the passage 89. From the passage 89' the air at atmospheric pressure extends through the longitudinal passage 87 to the passage 93 and the right-hand end of the working chamber 13 where it acts upon the pressure unit to cause it to move from a position, as illustrated in Fig. l, toward the left. At the same time air in the left-hand end of the working chamber 13 is evacuated through the passage 92, 86 and S8 into the central portion of the valve chamber 16 from which it is discharged through the aperture 84 into the line connected at the socket 82. When the seal at the righthand end of the unit uncovers the port 99, the air under atmospheric pressure enters the right-hand end of the valve chamber 16 and urges the valve unit bodily toward the left to the limit permitted, thereby placing the aperture S4 in communication with the aperture 89' and placing the aperture 83 in communication with the atmospheric port 95. Thereupon the action of the device is reversed so that air at atmospheric pressure entering port 95 enters passages 88', 86 and 92 into the left-hand end of the working chamber 13, and air under sub-atmospheric pressure which is drawn through aperture 84 is derived from or placed in communication with the right-hand end of the working chamber through the passages 89', 87 and 93. Therefore, it is apparent that by a slight change in location of the passages, as illustrated in Fig. 5, this device can be operated when connected to a source of suction, and possesses all of the advantages that can be secured when the device is operated by connection of the socket S2 thereof with a source of air at a pressure above atmospheric pressure.

Operation of the device by a difference in pressure between atmospheric pressure and sub-atmospheric pressure can be effected with the device constructed as illustrated in Fig. 1 by using port S4 as the high pressure port and ports 94 and 95 as the low pressure ports. In other words when ports 94 and 95 are connected to a suction line and port 84 is open to atmospheric pressure, the device will operate satisfactorily when the arrangement of the ports and the construction of the valve is the same as that illustrated in Fig. l. It will be apparent that this can be accomplished easily by the provision of a manifold communicating with the ports 94 and 95 and in turn connected to a line leading to a suction pump. As well understood in the art, such a manifold may be formed integrally in the valve housing or it may be provided as a separate part.

In cases where the device is to operate in iresponse to the difference in pressure between atmospheric pressure and sub-atmospheric pressure, a problem exists which is not present when the device operates in response to difference in pressure between compressed air and air at atmospheric pressure. That problem consists of maintenance of a sub-atmospheric pressure condition in the working chamber 13 between the two annular seals 54 carried by the spaced cylindrical end members 50 of the piston unit. This is necessary to insure proper positioning of the valve stem 70 as by avoiding entry of air at atmospheric pressure into the right-hand end of the valve chamber 16 through the port 99 while the valve is in the position illustrated in Fig. l. Various means may be employed to provide such a pressure condition. One such means would consist of providing an airtight seal between the cover plate 44 and the housing 10 at the access opening 40 and between the collars 26, 2S and the shaft 30. A device, provided with such seals and having air evacuated from the portion between the seals 54 after assembly of the device, would maintain a sub-atmospheric condition between the seals 54 as long as the casing 10 of the working unit remained leakproof. Such construction would be subject to certain inherent disadvantages, as will be apparent, and, in particular, would be subject to objectionably high cost of manufacture and to disability in the event even a slight leak were to develop which would result in the existence of an atmospheric pressure condition between the two seals 54.

Avoidance of some of the expense entailed in the procedure just above mentioned for maintaining a subatmospheric condition between the seals 54, and particularly avoidance of the step or operation of evacuating the portion of the working chamber 13 between the seals 54 after assembly of the device and before use thereof, may be accomplished by a simple expedient. Thus, if the central portion of the working chamber 13, that is, the portion between the innermost positions of the two seals 54, is placed in communication with the suction line, a satisfactory operation will result and a sub-atmos pheric pressure condition in the working chamber 13 between the seals 54 will be insured at all times when the device is in condition for operation. The working chamber 13 may be connected in communication with the suction line by a manifold (not shown), as will be apparent. Another means of accomplishing this purpose is to provide a port in the wall 96 separating the chambers 13 and 16 in such a position that it always remains in communication with the suction line. Thus, as illustrated in Fig. 5, the port 100 is shown as located in the same longitudinal position with respect to the valve unit and the valve chamber 16 as is the port 84. Consequently, the movement of the valve stem and its seals between its two operative positions will not affect or change the pressure condition at the port 100, and a sub-atmospheric pressure condition will exist in the part of `working :chamber '13 'between xthe seals 54 Jaft all time-s that -a sub-atmospheric pressure lcondition exists in the line connected with the port 84. The same expedient may Aalso lbe used lin cases-.where the Fig l construction is 'converted yfor lconnection and operation 'by a `source -o'f subaatmospher'ic pressure, but in this instance the port or ports ycompared `to rthe port d() of IFig. 5 should be located in `the same longitudinal orientation as lis one of the two ports 94fand l95. 11n the 'latter connection, a lpreferred construction would entail the Lformation of two ports compared to the port 100, vone 'in the same longitudinal orientation 4-as the -port '94, and -the other in the same longitudinal orientation as rthe port 95.

While the preferred embodiments of the 'invention have been illustrated herein, it will 'be understood that changes may be made in the construction-withinthescope of the appended claims without departing from Athe-spirit of the invention.

I claim:

l. A -u'idpressure motor comprising a housing having a valve chamber Aand a working chamber, a `valve shifta'ble in said valve chamber, apressure responsive `member shitable said 4working chamber, 'said housing having a iiuid intake vand -a pair of -uid 4outlets each 'communicating with said valve chamber, Va jpa'ir of Ypassages each communicating with said valve chamber adjacent to said :inlet and an outlet, said passages communicating with opposite portions of said working chamber, `said valve controlling fluid vow between said inlet, Isaid outlets and said passages, and ports connecting said chambers and spaced :from the opposite ends thereof, said pressure responsive member controlling 'fluidow through said portS, saidvalve chamber being cylindrical yand said valve -constituting a spool having a plurality of longitudinally spaced circumferential seals, the end seals of said valve being interposed 4between the adjacent port and the adjacent outlet in all positions of said valve.

2. A -uid pressure motor comprising a Vpower unit having a 'working chamber shiftably receiving an oscillatable pressure responsive element, .a valve unit .having a chamber shiftably receiving a'pressure responsive valve member having two operative positions, and a fluid circulating system having inlet and outlet -ports and passages connecting said chambers with each other, said valve conneet-ing one passage to inlet and the other to outlet in each operative position and reversing said `connections when shifted from one position to the other, said chambers having a common wall ,and a second pair of .passages connecting said chambers, said second passages being formed 1in said common wall and positioned adjacent to but outwardly of the innermost operating positions of .the

opposite ends of said pressure responsive element whereby each is uncovered to admit iluid under pressure ,into s aid valve chamber to shift said valve member as the working element 4approaches an end of l'its stroke, said second passages being positioned outwardly O the adjacent portion of said valve member in all positions thereof.

-3. A fluid pressure motor comprising a power ,unit having a working chamber shiftably receiving an oscillatable pressure responsive element, a valve unit having a chamber `s hiftably receiving a reciprocable `spool valve member ,having vtwo operative positions, said valve mem ber .having a plurality ,of spaced/circumferential seals in- .termediate its length,J niet and outlet ports conunurcating with the intermediate portion of said valve chamber in longitudinally spaced relation, va pair of passages each communicating with the intermediate portions of said valve chamber spaced longitudinally from each other and from said inlet and outlet ports, said passages communicating with opposite ends of said working chamber, and a pairof ports each connecting an intermediate portion of said working chamber -witfh an end portion of said valve chamber spaced longitudinally from the aforementioned ports -vand passages .and :outwardly '-o'f th'e respective :'adja-l cent end seals -of tsaid valve Vin all 4positions ofuthe valve.

4. duid 'pressure motor comprising -a power unit having a working chamber `s'h'ittably receiving 1a rcipro cable pressure responsive felementhaving spaced head portions land an intermediate portion, Ja valve unit thaving a chamber shifta'bly receiving a pressure responsive valve member, a 'iiu'id circulating system including an :inlet opening anda pair of-outlet openings and a'pairof passages Aconnecting Athe opposite lends o'f `said lworking chamber with said A-valve Ichamber land Icontrolled by said valve member for alternate communication with said inlet and out-iet openings, and passage means connecting said chambers 'and :isolated Iat all times 'from said 'outlet openings "by 'sa'id valve, `said last vnamed lpassage means being controlled lby said pressure responsive element 'Lto admit -iuid under pressure from said `workin g 'chamber to said valve :chamber lfor actuation of 'sa'idvalve 'member as said power element lapproaches one end of "its `movement in Jits chamber, ya driven'member iournaled Min said working lchamber `transverse df and :intermediate the 4length of said working chamber, and a "drive connection between said Idriven member and the intermediate portion lof 'said pressure responsive element.

5. A pneumatic motor comprising a housing 'having a valve chamber 'and a working chamber, said chambers being elongated and juxtaposed, a s pool valve .shiftable in said valve chamber between two operative positions, a pressure responsive member oscillatable in said working chamber between opposite limit positions, and a 'fluid circulating 7system including inlet and outlet openings communicating with said valve chamber, and 'two pairs of passages connecting said chambers, :the passages of one pair being controlled by said valve and connecting the opposite .ends of said Working chamber outwardly ofthe limit positions of said pressure responsive member Aalternately with said inlet `and outletports, the passages of the other pair being controlled by said pressure responsive member to selectively admit iiu'id into said valve chamber to shift said valve 'as said 4pressure ,responsive member approaches each limit position said Aspool valve .having four longitudinally spaced seals located to alternately connect the passages of said li-rst pair with .said inlet and outlet openings and to ,isolate the passages of the other pair from Ythc adjacent outlets at Aall times.

6. A fluid pressure `motor as ,deiined in claim ,2, adapted to .operate in response to a pressure -dilerence between atmospheric pressure and `sub-.atmospheric pressure, wherein said pressure responsive element has longitudinally spaced seals, said inlet and outlet ports includ- 'ing two 'inlet ports Iconnected to atmosphere and an .outlet port Yconnected to a Asource of sub-atmospheric pressure, and passage means adapted to .connect to a subatmospheric pressure source the central portion .of working chamber located between `the innermost positions of the seals of said pressure responsive element, `the passages of Ysaid .second pair serving to admit atmospheric pressure to said valve chamber tor shifting saidv valve member as the working element approaches :the end of Aits stroke.

7. A liuid pressure motor as defined `in claims 3 .and 6, wherein the passage means communicating with the central portion of Ysaid working chamber .also couuuunicates with a portion of said valve chamber which is in continuous communication with Asaid outlet portanti a sub-atmospheric pressure source.

.8. Auid pressure motor comprising a housing having a valve chamber and a working chamber, ya valve shiftable lengthwise in said valve chamber between two openative positions and having aV plurality ofl seals spaced lengthwise and spaced rornthe opposite ends of the valve, a pressure responsive member oscillatable in said working chamber between opposite limit positions, and a fluid circulatingl system including inlet .and outlet openings communicating with and spaced lengthwise of said valve chamber, a pair of passages spaced lengthwise from said inlet and outlet and controlled by said valve and selectively communicating with said inlet and outlet and with an end portion of said Working chamber outwardly of the limit position of said pressure responsive member, and a pair of ports each establishing communication between a portion of said valve chamber spaced lengthwise from the aforesaid openings and passages and an end portion of said working chamber inwardly of the limit position of said pressure responsive member in said working chamber, each port being isolated from the adjacent outlet by said valve at al1 times, said last named ports alternately communicating with said inlet and outlet openings through s said valve in operative reversals thereof.

UNITED STATES PATENTS Bromley Feb. 26, Marsh Aug. 27, Frost Feb. 11, Rhodes Ian. 3, Weinman Sept. l2, Phillips, Jr. Apr. 17, Armstrong et al. Nov. 16,

aid working chamber to maintain position by uid pressure between 

